Growing up, I was really into horses. I collected model horses, and I have well over 100 of them. They are still on shelves collecting dust in my old room at my parents’ house, and everytime I visit they tell me I need to deal with the model horses. When I get the time and energy, I’ll probably package them up and sell them on eBay. Turns out there is a huge collector’s market for them, and the ones in my collection are all discontinued and some are quite rare.
Kid, the Younger wants me to say that he collects train stuff (models, rail spikes, pictures etc), tools and lawnmowers, including a couple of ride-ons.
I e-Bayed my way to a small paperweight collection (approx. 30) when I had money. My favorites are by John Hamon-Miller of Hannibal, MO. I would love to see his studio someday.
I’ve accumulated over 100 (maybe 150 by now) refrigerator magnets. Some are store-bought and some I’ve made with cross-stitching or just things I’ve found.
It’s amost time for me to go into my Christmas ornament collecting frenzy again. Wish I had more money. sigh I plan to pass these on to my little nieces when they’ve grown up.
I rescued a pair of home-made flamingos because it seemed too cruel to throw them out (they disappeared years ago). But people started giving them to me, and then I found a few very lovely ones myself …
How did it start with you?
I collect old Jeep and Willys magazine ads. I currently have: a 1906 ad for the J.N. Willys Company of Elmira, NY, two Overland ads (1917 and 1925), one Americar ad (1940), four World War II Model MB ads (1943-1944), two Jeepster ads (1948 and 1949), two Jeep Station Wagon ads (1948 and 1951), a 1953 CJ-3B ad, a 1954 Aero ad, two CJ-5 ads (1955), two Wagoneer ads (1965 and 1968), and two CJ-7 ads (1975 and 1979).
My God man - you are truely lost!
Lord, forgive him, he knoweth not that he sins…
[sub]Death to the mouse and all his kin![/sub]
Folding pocket knives under 4 inches in length. Succulent plants.
Gideon Bibles.
Motorcycles, currently I have 3, a 1966 BSA A65H, a 1952 Triumph TRW and a 1936 BMW R2.
Wheat pennies, I have about 7 gallons right now.
Inline motorcycle trading cards.
Records, about 700 now, I thinned out when we moved, now I have a collection of “bad” records.
I accumulate a lot of stuff but most of it is for eventual resale (silver ingots, brass grease guns, motorcycle trading cards, British and European motorcycle parts).
unclviny
I collect dust too! Do you have particle #634-842-A? I NEED that dust!
Netsukes…those cool mini handsculpted japanese things.
Mad magazines 
…i got about 300 from america, australia, england and one from Germany. They all contain different material, even the ones with the same cover and number.
I also have a small collection of Spike Milliagan books, about 20.
I have a small collection of live computer viri. They have to be found infecting an aquantence’s computer as opposed to downloaded specifically. I only have a hand full around 10.
Max Racks cards and Go cards, around 250 of them. I’ve only picked them up in NYC but I’m pretty sure they have them in other cities.
Polished stones. I think I’ve got 50-60 of them. You can’t take me to a Nature Company type store without me buying a handful of them, my friends mock me. 
I was going to include my QUART of wheat pennies/silver, all collected in change. I’m glad I didn’t now.
The pink flamingoes thing started because I’m a native Floridian, transplanted to NJ. I even have one in the form of a X-Mas tree ornament. I keep them in the kitchen, where they can flock together…
Colophons, Chick Tracts, and hosta.
Didn’t notice any of the geekier collectors checking in (although I just skimmed, so maybe I missed someone.)
Here we go:
Star Wars Figures
Star Wars Beanie Buddies
Star Wars Lego sets
Comic books (not hardcore, only 3 or 4 active titles at a time.)
Board Games
Ravenloft products (a Dungeons & Dragons setting)
Magic: The Gathering cards (off and on. Currently off.)
Back when I was a teenager, I managed to talk my parents into allowing a beer can collection. I had about 3000 unique cans before I eventually gave it up and sold out to a friend when I went off to college. I had some really good cans, I wish I could get that collection back now. I also collected some football cards and comic books before that, but nothing very substantial.
I don’t really collect anything now. Over the years I picked up a couple of non-collecting hobbies and really don’t have time for it anymore.
Jammer
SF books and magazines. I have somewhere around 6,000 (I’m in the process of indexing them.) It is a collection, not an accumulation, because I buy to fill in gaps, not because of quality.
I accumulate jigsaw puzzles, especially map themes. No idea how many, just too many.
Well, I have collected original animation art - and coins. And lots and lots of books.